Mark Kerrigan, 45, is expected to be arraigned today on one count of assault and battery on a person over 60, according to a report from the Boston Herald.
Nancy's mother, Brenda, told the Herald that her husband died of heart attack.
A police report states that the two men were arguing and pushing each other before the elder man fell back.
The report says Mark put his hands "around his father's neck" and accused him of "faking it" when he fell. He also had to be subdued by pepper spray and appeared intoxicated, according to the report.
The argument was apparently about use of the family's telephone.